Even as the FN conference, aimed at reviving and unifying the party after its 2017 defeat to Emmanuel Macron, drew to a close on Sunday, the arguments and threats of legal action over the name were beginning.

Critics also questioned whether FN leaders had suffered collective historical amnesia in choosing a name that harks back to Nazi-supporting and extreme right organisations, or had picked it deliberately.

“Dear Marine, the RN (Rassemblement National) already exists and you can’t deny its existence when it has stood against your candidates several times since 2014,” Kurek wrote.

“The RN is Gaullist and republican right, the FN is extreme right. The FN will NEVER be the RN and the RN will NEVER be the new FN,” he concluded.

A few hours later, Le Pen announced she was suing Kurek for “fraudulent use” of the FN’s flame logo as his party’s symbol.

Le Pen told RTL radio on Monday that her party had registered the name Rassemblement National in 1986 and had the right to use it.

Kurek, however, went on Europe 1 radio to declare: “Once again, Marine Le Pen has made a beginner’s error … that’s not how it works. We’ll go to court, no problem.”

He said he would be fielding candidates in the 2020 municipal elections under the RN name and logo.

The word “rassemblement”, meaning rally, union, gathering, has appeared a number of times in centre-right so-called Gaullist party names since the war.

Charles de Gaulle founded his Rassemblement du Peuple Français (RPF) in 1947, which existed until 1955. In 1976, Jacques Chirac created the Rassemblement pour la République (RPR) and in 2014, his successor as president, Nicolas Sarkozy, considered calling the centre-right opposition party Le Rassemblement. It has since become Les Républicains.

Its historical use is also more extreme. The Rassemblement National Populaire (RNP), whose logo – like the FN – showed a red, white and blue flame, was founded by the second world war collaborator Marcel Déat with a party logo that bore a resemblance to the Nazi swastika.

The name was also used by Jean-Louis Tixier-Vignancour, an extreme-right lawyer who stood in the 1965 presidential election. Tixier-Vignancour’s campaign was run by Jean-Marie Le Pen, Marine’s father and the FN leader from 1972 to 2011.

Alexis Corbière, of the hard-left La France Insoumise (Unbowed France) party, questioned whether the choice was deliberate, while Bruno Dive, a journalist with Sud Ouest, wondered if Le Pen and her team “lack any knowledge of history”.

Le Pen’s estranged father, excluded from the FN and stripped of his honorary president title in a change of party statutes at the weekend, said the name change “lacked imagination” and was a “political assassination” of the FN. He said he had used Rassemblement National twice in elections in the 1980s.

Bruno Gollnisch, an FN veteran and political ally of Le Pen senior, was also dubious.

“I have my reservations because under the name Front National we have made enormous sacrifices. In general, parties change their name to make people forget their sins … the Front National has never lacked honour and probity,” Gollnisch said.

“I would be favourable to a name change if this evolution was part of a new reality, meaning alliances. If the party is making alliances it’s normal it adopts a title that is not purely FN.”

In her conference closing speech, Le Pen said party members would vote on the name change in the comings weeks. If she loses in court, she may have to fall back on Alliance pour un Rassemblement National, a name registered by her deputy Louis Aliot in 2012.